Souya Minamino (南野 宗谷,Minamino Soya?) is one of Hayate and Ayumu's friends who attends Hayate's previous high school, Shiomi. According to Ayumu, he's really (and only) good at swimming. He is also the protagonist of Kenjiro Hata's previous work, Heroes of the Sea Lifesavers.
On December 24th, while on their way to a Christmas party, Souya and his friends meet up with Hayate and try to invite him to come along, which he declines saying that he has no money and he's on his part-time job. Much to their annoyance they start to question him about his dedication to work which Hayate states his parents are unemployed, afterwards Souya and his friends leave ultimately feeling sorry for Hayate.
Later on January 10th Souya and his friend Hijiri, encounter Hayate with Ayumu at the enterance of Shiomi High school. After finding out from a teacher that due to his parents asking for the remainder of his school fees, Hayate is now a drop out, Then much to his surprise, Souya witnesses Ayumu confess her feelings to Hayate before getting slapped by her after turning her down.
Later in Febuary, Souya and his friends from Shiomi run into Hayate, after catching up with him at a restaurant they unwittingly leave Hayate with their bill for 50,000 yen. A few days later, Souya visits the Sanzenin Mansion to repay Hayate for their restaurant bill.
Souya later makes a small cameo in Ayumu's flashback in chapter 114, while standing in an arcade with Hijiri, where they overhear Ayumu ask Hayate if he can take a photo sticker with her.
During Golden Week, while exploring the underground water tunnel with Nagi, Ayumu mentions that she learned a lot from a book on swimming that she once borrowed from Souya.
Later on May 15th Souya encounters Ayumu, after asking him on what day it was, Ayumu leaves depressed seeing he didn't remember her birthday.